The majority of present day integrated circuits (ICs) are implemented by using a plurality of interconnected field effect transistors (FETs), also called metal oxide semiconductor field effect transistors (MOSFETs), or simply MOS transistors. An MOS transistor includes a gate electrode as a control electrode and spaced apart source and drain regions between which a current can flow. A control voltage applied to the gate electrode controls the flow of current through a channel between the source and drain regions.
The gain of an MOS transistor, usually defined by the transconductance (gm), is proportional to the mobility (μ) of the majority carrier in the transistor channel. The current carrying capability and hence the performance of an MOS transistor is proportional to the mobility of the majority carrier in the channel. The mobility of holes, the majority carrier in a P-channel MOS (PMOS) transistor, and the mobility of electrons, the majority carrier in an N-channel MOS (NMOS) transistor, can be increased by applying an appropriate stress to the channel. The known stress engineering methods greatly enhance circuit performance by increasing device drive current without increasing device size and device capacitance. However, as technology is scaled down and as each device in the IC and each element of each device is reduced in size, the volume of stress sources becomes smaller and smaller, which makes using strain engineering to enhance device performance more and more challenging.
Accordingly, it is desirable provide a method for fabricating a stress enhanced MOS transistor. In addition, it is desirable to provide a method for fabricating a stress enhanced MOS transistor by a process of memorizing or maintaining the stress introduced into the transistor channel by a stressed dummy gate electrode. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.